The present invention relates to winding coils of electric dynamo machines. In particular, the solutions of the invention relate to winding poles of cores where the slots for receiving the coils have external openings.
The turns of the coils are wound by at least one dispenser arm capable of delivering wire on the surfaces of wire guide members, where the wire runs to reach predetermined positions in the slots. The final winding result requires that the wire of the turns be deposited in the slots according to a predetermined disposition, therefore not randomly.
The turns of the coils are positioned during winding according to a required disposition to optimize the quantity of conductor wire that can occupy the available space of the slot. Furthermore, the turns should not cross each other, or be excessively deformed locally to avoid damaging the wire insulation.
The disposition of the turns around a pole foresees progressively winding a series of turns in the radial direction of the core. One turn is wound along the sides and along the axial ends of the pole. The sides of the pole delimit a slot. The succession of turns wound in this manner forms a layer of turns. Within the layer, the turns have a so called “radial stratification”; in other words a disposition where the turns are one next to the other in the radial direction of the pole that is being wound.
To complete the coil further layers are formed. In each further layer the turns are again wound one next to the other in the radial direction of the pole. A further layer is formed above the layer wound previously, therefore positioning of the successive layers occurs in an angular direction of the core to form the so called “stratification of the layers of the turns”.
In a same slot, there will be positioned portions of two coils (layers of turns). Each portion of a coil is wound around a pole that is adjacent to two poles. Therefore, there are specific portions of the slot space occupied by respective coil portions of coils, and there is a certain part of the slot space which remains empty. This empty part is a delimitation area between the portions of the coils wound in the same slot. The empty portion is radially aligned with the opening of the slot where the wire passes to enter the slot during winding.
Winding in this context may require connection of the coil leads to termination structures of core, like tangs or other devices, where the wire needs to be connected, for example by wrapping or insertion techniques.
Machines and methods for winding coils in the context described above are described in U.S. Pat. No. 6,848,646. In this case, the solution foresees a dispenser arm that rotates around the poles to dispense the wire forming wire turns. The wire leaving the dispenser arm is intercepted by a wire guide assembly, which is aligned with the aperture of the slots and with the position of the pole where the turns being wound need to be positioned.
In the solution of this document no parts of the wire guide enter the slots of the core, and the part of the wire guide that guarantees the radial stratification of the turns along the pole is progressively distanced from the axial end of the core, as the layers are formed in order to perform depositing of the wire correctly.
The solutions of publication EP 1420505 make use of a needle provided with translation motion, and rotation of the core to wind the turns around the poles. If the needle is sufficiently narrow, it can be made to pass though the openings of the slots, and therefore the needle can accomplish deposition trajectories producing radial stratification.
The needle solution has a trajectory consisting of translations combined with rotations with respect to the core. The resulting trajectory has stretches where loss of tension occurs on the wire (particularly for a wire that is greater than a certain diameter) due to an excessive release of wire from the needle.
The stretches of wire where this release occurs are difficult to position around the pole. Furthermore, the size of the needle thickness that enters the slot and occupies the empty portion of the slot, which delimits the portions of coils present, impedes a maximum and optimized filling of turns with respect to the available space.
The solution of the present invention are capable of achieving the maximum filling of turns in the slots using a stratified disposition in the radial direction and of the layers in the angular direction.
Furthermore, the solution of the present invention is capable of achieving connection of the coil leads to termination structures of the core.
In relation to termination solutions, EP 1,353,436 describes solutions for accomplishing connections of the coil leads to termination structures of the core using a rotating flyer arm for winding and a wire guide for accomplishing radial stratification of the turns along the pole.